The present invention relates to an apparatus for fluid treatment of yarn by forcing fluid into a running multifilament yarn, for specially entangling multifilaments. It further relates to a yarn composed of entangled multifilaments produced by the apparatus.
Multifilament yarn produced by a high molecular polymer generally has is poor filament coherency, requiring treatment to impart coherency. Conventional methods for imparting coherency include twisting the yarn, sizing the yarn, and fluid entanglement.
Fluid entanglement is often used, because it is easy to impart desired properties of compactness or bulkiness to the yarn as spun. The requisite equipment is simple.
Fluid entangling devices are often called entangling devices, entangling nozzles or interlacing nozzles, etc.
The conventional entangling nozzle comprises a nozzle block, a yarn passage formed in the nozzle block and having a yarn inlet and a yarn outlet in the outer surface of the nozzle block, and also a fluid passage formed in the nozzle block and having a fluid inlet in the outer surface of the nozzle block and a fluid outlet in the inner wall surface of the yarn passage.
The yarn is run at a desired speed and tension, through the yarn passage, and encounters a fluid (fluid jet) injected at a desired pressure, velocity and flow rate from the fluid passage. This causes the filaments constituting the yarn, to be displaced relatively each other and entangled, and a yarn composed of entangled filaments is produced.
The yarn is simply called a tangled yarn. Depending on the treatment conditions selected, a compact yarn or a bulky yarn can be produced. An entanglement measuring instrument for measuring the degree of entanglement of filaments is known and used. Also, a bulkiness measuring instrument is used for that purpose.
To improve the entangling capability of the entangling nozzle, various nozzles and methods have been proposed.
For example, an entangling nozzle in which a cross-sectional configuration and area of the yarn passage are changed in the longitudinal direction has been proposed. Furthermore, to obtain a high degree of entanglement, it has been proposed to force a compressive fluid of higher than the critical pressure through a fluid passage at a supersonic velocity with a specially formed cross section to a running yarn.
These proposals are disclosed in Japanese Patent Laid-Open (Kokai) Nos. 54-30952 and 48-1340 and Japanese Patent Publication No. 36-10511.
These conventional entangling nozzles have a narrow throat in the cross section of the fluid passage, which increases the velocity of the fluid, in order to achieve a high degree of entanglement.
However, since the fluid passage is a thin or fine hole having a diameter of only several millimeters, it is very difficult to form a highly accurate throat in the hole. Accordingly, the entangling capability differs from nozzle to nozzle among the many nozzles produced. As a result, it is an inevitable problem that the entangling capability and degree of yarn entanglement differs from nozzle to nozzle among many entangling nozzles used in a production.